Dun Laoghaire-Rathdown County Council has confirmed that there was an effluent overflow from a pumping station adjacent to Seapoint but has not yet given full details about the incident.
A spokesperson for the authority confirmed that there had been an overflow from the station on August 19, but stopped short of providing specific information on the quantity or seriousness of the discharge.
The confirmation comes after serious concerns were raised that a foul-smelling brown sludge, which appeared in the sea off south Dublin, could be sewage overflowing from a nearby pumping station.
But now, Dun Laoghaire Rathdown County Council has moved to alleviate fears that the mysterious brown sludge and foul smell is linked to the pumping station overflow incident and insists that it is the result of natural occurring brown algae which has made its way onto the beach.
"As far as I know the overflow occurred when the pump in the pumping station was beaten [by the amount of material that it had to pump] and that happened because of the heavy rainfall," a spokesperson said.
However, when asked to give details on the material that had made its way into the sea, which is a popular bathing spot for thousands of southside residents, the spokeswoman declined to comment.
When questioned about what had caused a number of readings to rise above the Blue Flag limit on August 14 last month, five days before the overflow occurred, the spokeswoman stated: "This is a bay and therefore a natural environment with human, animal and plant activity that is not within the control of the local authority.
"Dun Laoghaire Rathdown County Council wishes to reiterate that independent sampling by Dublin city central laboratory has confirmed that the water quality on our two Blue Flag beaches at Seapoint and Killiney meets the stringent standards set by the Blue Flag criteria."
She continued: "These standards are considerably in excess of Irish natural regulation and mandatory standards as determined by the EU bathing water directive and Irish national regulation limits."
The council spokeswoman was keen to point out that the readings which occurred on August 14 were in no way related to the subsequent overflow which took place on August 19 or the appearance of a brown sludge which has been observed by locals in the area over the past two weeks.
Meanwhile, the Environmental Protection Agency (EPA) carried out a number of tests in the water at Seapoint last Friday, after been contacted by the Sunday Independent.
The agency subsequently confirmed that the brown sludge that is currently present in the water is in fact a strand of brown mackerel algae otherwise known as Ecto carpus pylaiella.
Speaking about the results of the tests, a spokeswoman said, "One of our inspectors completed the investigation and it seems that the sludge is in fact a band of brown mackerel algae which has been stranded on the sea shore.
"It is a naturally occurring and, while it doesn't look pretty, it actually isn't of any issue, apart from the odour."
The environment agency also stated that it will be carrying out further, more detailed examinations, over the next week.
But despite reassurances from local authorities and environmental agencies, locals were still cautious about going for their regular swim last week.
A number of children who were playing in the water at Seapoint spoke of how they had heard rumours about the sludge and said they felt sick after swallowing the water.
Thirteen-year-old Kim Joyce from Blackrock complained that the odour was making her feel unwell.
"You can smell it all the way up at our house. It makes me feel sick, and my little brother, who is only two years of age, got sick from the smell of it. I also have a rash on my legs and I think that might be from the water."
Her friend, Adam Kane (12) agreed: "It's rotten when you swallow the water. But we've nowhere else to play except the park and that's not as good.
"We'd like if the water got cleaned out so we wouldn't have to worry about going for a swim anymore.
Local businesses, such as the Purty Kitchen restaurant, are very keen that the problem of the foul odour should be addressed urgently.